e181. creating a file lock on a file.txt

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The behavior of the file lock is platform-dependent. On some platforms, the file lock is advisory, which means that unless an application checks for a file lock, it will not be prevented from accessing the file. On other platforms, the file lock is mandatory, which means that a file lock prevents any application from accessing the file. 
    try {
        // Get a file channel for the file
        File file = new File("filename");
        FileChannel channel = new RandomAccessFile(file, "rw").getChannel();
    
        // Use the file channel to create a lock on the file.
        // This method blocks until it can retrieve the lock.
        FileLock lock = channel.lock();
    
        // Try acquiring the lock without blocking. This method returns
        // null or throws an exception if the file is already locked.
        try {
            lock = channel.tryLock();
        } catch (OverlappingFileLockException e) {
            // File is already locked in this thread or virtual machine
        }
    
        // Release the lock
        lock.release();
    
        // Close the file
        channel.close();
    } catch (Exception e) {
    }